The liquid-vapor water generation characteristics of thermo-responsive polymer based on the multi-scale method

Thermo-responsive polymer is becoming a potential water purification and water harvesting material. To clarify the water diffusion characteristics, the desorption ratio of liquid water and water vapor for a poly (N-isopropylacrylamide) was researched by the multi-scale method. Firstly, macro and micro structures for the hydrogel with different water content were characterized. Second, the dynamic moisture preserving status of the hydrogel during the desorption process were tested. Thirdly, the dynamic liquid-vapor desorption rate was quantified. The macro volume of the polymer is of liner relationship with water content. During the desorption process, free and immobilized water transfers to immobilized and bound water. About 80% of the purified liquid water can be collected directly in closed environment, while the amount decreased to 21%–25% in air convection condition. The results suggested a heating method for improving liquid water collection rate with low energy cost for practical applications. [Display omitted] •Micro-macro method used for the structure and desorption of a thermo-responsive polymer•Free and immobilized water become immobilized and bound water during desorption•Liquid water desorption ratio is 80% and 21% in close and air convection condition•15.4 g kg−1·min−1 liquid water can be collected directly in a closed environment Macromolecules; Materials science; Polymers